1. Field of the Invention
This invention relates to a punching apparatus having a tool support arm pivotally connected to the punching apparatus for moving a tool holder with a punching tool retained therein between a tool punching position and a tool changing position and more particularly to a punching apparatus having a valve controlled actuator mechanism that swings the tool support arm and attached tool holder between the tool punching position and the tool changing position where the swinging movement of the tool support arm is coordinated with the engagement of the tool support arm to the press frame of the punching apparatus.
2. Description of the Prior Art
Conventional machines for perforating sheet metal include a worktable supported by the lower portion of a press frame with a ram punch positioned vertically above the worktable in the upper portion of the press frame. A suitable punching tool is positioned below the ram punch above the workpiece. Vertical movement of the ram punch moves the punching tool into and out of engagement with a die that is rigidly supported on the worktable. A tool support for positioning the punching tool in vertical alignment with the die is secured to the press frame above the worktable. In this manner, perforations of various shapes and sizes are made in the workpiece.
U.S. Pat. No. 3,270,605 discloses a clamping device by which the tool holder locks the punching tool in coordinated relation with the die. By manually releasing the clamp, the punching tool may be removed from the tool support. With this arrangement, the machine operator is required to use both hands in releasing the tool support from the frame or the punching tool from the tool holder. The steps of releasing the tool holder from the press frame and moving the tool support from coordinated relation with the die must be manually and separately performed.
A tool support holder, illustrated and described in U.S. Pat. No. 3,405,581, is releasably locked to a carriage and is movable with a carriage between an extended and retracted position. The carriage travels horizontally on rails positioned parallel to the upper portion of the press frame. With this arrangement, the carriage with the tool support holder is manually moved on the rails in a front-to-rear direction relative to the press frame for moving the tool support holder into and out of punching position. U.S. Pat. No. 3,745,646 discloses a tool changer for a multiple-hole turret press in which a punch and die of a fixed size are loaded into a tool holder that is arranged to rotate about a vertical axis from a tool loading position to a tool punching position.
There is need for a punching apparatus that has a tool holder releasably connected to the front end portion of a tool support arm that is pivotally connected to the press frame of the punching apparatus and is mechanically moved between the tool punching position and the tool changing position. In this manner, tools may be replaced in the tool holder or the tool holder changed on the tool support arm rapidly and efficiently without requiring the operator to manually move the tool support arm. The pivotal movement of the tool support arm should be coordinated with engagement of the tool support arm to the press frame so that the swinging movement of the tool support arm is coordinated with release of the tool support arm from the press frame to move the tool holder into and out of punching relation with the die.